A letter from Kim Jong-un, the North Korean leader, expressing his condolences on the death of a former South Korean first lady was delivered to South Korean officials at the countries’ border on Wednesday by Kim’s sister, officials said.

The brief meeting between Kim’s sister, Kim Yo-jong, and the South’s national security adviser, Chung Eui-yong, who received the letter, was a rare high-level contact between the Koreas at a time when talks over the North’s nuclear program have stalled, although there was no indication that the two had held substantial discussions, nytimes.com reported.

The former first lady, Lee Hee-ho, who died on Monday, had visited North Korea a few times and once met Kim. Her husband, the late South Korean president Kim Dae-jung, championed the so-called sunshine policy of encouraging political reconciliation and economic cooperation with North Korea.

At the meeting on Wednesday, Kim Yo-jong expressed hope that the two Koreas would “continue cooperation to honor the will of the late first lady Lee Hee-ho, who dedicated herself to inter-Korean reconciliation and cooperation,” Chung told reporters.

He said Kim did not bring a message from her brother, nor did the South’s President Moon Jae-in use the contact to send one to Kim Jong-un. The North Korean leader has sent his sister to the South in the past as an envoy, and news of the pending meeting had led to speculation that she might be bringing a message about the stymied nuclear talks.

Lee, the late first lady, who was also a prominent campaigner for women’s rights, accompanied her husband to Pyongyang, the North Korean capital, in 2000, for the first-ever summit talks between leaders of the two Koreas. When the North’s then-leader, Kim Jong-il, died in 2011, Lee returned to Pyongyang for his funeral, where she met Kim Jong-un, his son and successor.

North Korea had also sent a delegation to South Korea for Kim Dae-jung’s funeral in 2009. Such history led the South Korean news media to speculate this week that Kim Jong-un would send another delegation for Lee’s funeral on Friday.

Moon’s effort to broker a peace and denuclearization deal between North Korea and the United States has been jeopardized since February, when talks between Kim Jong-un and President Trump in Hanoi, Vietnam, abruptly ended. But he is eager to revive his role, saying in April that he would meet with Kim at any time or place to discuss how to break the stalemate.

North Korea has been unreceptive, demanding instead that South Korea defy the United States and push for the expansive inter-Korean economic projects that Moon says he wants. Moon’s government has said it agrees with Washington that such projects cannot proceed until Pyongyang takes meaningful steps toward denuclearization and international sanctions on the North are lifted.